1. Field of the Invention
This invention relates generally to enhanced trajectory tracking of an automobile and, more particularly, to a method for relative positioning of a host vehicle with respect to surrounding static obstacles and moving targets which uses object detection data along with vehicle dynamics data to compute a closed loop trajectory of the host vehicle, and uses the trajectory in path planning for collision avoidance or other purposes.
2. Discussion of the Related Art
Many vehicles now include systems which can actively control the path of the vehicle—for applications such as collision avoidance. These systems, when they detect a need to alter the path of the vehicle, will determine a desired new path for the vehicle to follow, implement braking and/or steering commands to achieve the desired path, monitor the actual trajectory of the vehicle relative to the desired path, and make further corrections to follow the desired path—all in real time.
In such systems, it is essential that a reliable method of monitoring the actual trajectory of the vehicle is available. Many vehicles equipped with such systems use vehicle dynamics sensors—including velocity, yaw rate and acceleration sensors—as one means of calculating actual vehicle trajectory. However, vehicle dynamics or “dead reckoning” calculations are susceptible to cumulative error. Therefore, another source of vehicle trajectory data is needed—preferably a source which does not accumulate error like the vehicle dynamics data. Global Positioning System (GPS) data is commonly used as the second source of vehicle trajectory data in vehicle path planning systems. However, some vehicles are not equipped with GPS receivers, and even vehicle which are equipped with GPS receivers will sometimes have no signal available—such as in tunnels, “urban tunnels” and roads with tall and dense surrounding tree cover.